2.0 Analysis 2.1 Introduction During the investigation, neither the instructor nor the student could offer an explanation as to why the helicopter's tail rotor struck the ground so far short of the intended landing area. Adequate corrective action was not taken during the descent. The analysis will concentrate on the instructor's and the student's actions. 2.2 Actions of Instructor and Student Although the student had initially experienced some difficulty converting to rotary-wing flying, the instructor had flown more than 30 hours with him, and was satisfied that his performance met the required standards for a TC endorsement. The facts revealed on investigation are consistent with complacency and/or lack of vigilance throughout the final autorotation. Although the instructor was aware that the student had misjudged his altitude and distance and had allowed the helicopter to descend below the optimum approach path for the intended landing area, the instructor allowed the student to continue the autorotation to touchdown. The instructor did not take the appropriate corrective action in time to prevent the tail rotor from striking the access road, likely because the student had successfully performed the five previous full-on autorotations. The damage to the tail rotor blades and drive shaft resulted in a loss of directional control of the helicopter when a recovery was attempted, and the helicopter crashed. 3.0 Conclusions 3.1 Findings The student misjudged the altitude and distance from the intended landing area, initiated a steep flare, and did not level the helicopter prior to touchdown. The instructor allowed the student to continue the autorotation to touchdown and did not take the necessary corrective action in time to prevent a tail rotor strike. The tail rotor strike resulted in damage to the tail rotor blades and drive shaft, and loss of directional control. The helicopter was certified, equipped, and maintained in accordance with existing regulations and approved procedures. The instructor and student were certified and qualified for the flight in accordance with existing regulations. 3.2 Causes The student pilot misjudged the altitude and distance from the intended landing area during the practice autorotation, and the instructor did not take the necessary corrective action in time to avoid the tail rotor strike and subsequent loss of control of the helicopter. The Board has no aviation safety recommendations to issue at this time.4.0 Safety Action The Board has no aviation safety recommendations to issue at this time.